Why is my Windows Lumia 640XL speaker so quiet on full volume?

Listening to anything on the speaker in my Lumia 640 XL is very quiet even on full volume. It has been like this since new. It is audible but discriminates against anyone who does not have 20/20 hearing or does not have a quiet room to listen or wants to share the sound with another.

Is this a software problem that will be fixed soon to bring it up to the same standard as the older 630 model, which has great volume for a squeaker speaker? Any relevant help or advice would be appreciated.